The hazards to public health and the environment which are posed by a variety of synthetic halogenated organic compounds is well known. Compounds such as polychlorinated biphenyls (PCB's), dichlorodiphenyl trichloroethane (DDT), dieldrin, lindane and chlordane have been found to be persistent, environmentally toxic materials which require safe and efficient means of disposal PCB's pose a particularly serious disposal problem. Once widely used as dielectric fluid additives in electrical equipment such as transformers and capacitors because of their excellent insulating properties, the use of PCB's in many applications has been banned by the U.S. Environmental Protection Agency owing to their cumulative storage in the human body and extremely high toxicity. Thus, methods for the removal and/or destruction of halogenated organic compounds such as PCB's are required.
Various methods for the removal and/or the destruction or decomposion of halogenated organic compounds are known in the art. For example, the Peterson U.S. Pat. Nos. 4,447,541 and 4,574,013 disclose methods for decontaminating soil which is contaminated with halogenated organic compounds. The Peterson U.S. Pat. No. 4,447,541 discloses process in which a reagent mixture of an alkaline constituent and a sulfoxide catalyst (DMSO) are intimately mixed with soil contaminated with PCB's. The reagent mixture affects a desorption of the halogenated contaminants from the soil and subsequently dehalogenates the contaminants. However, this process is disadvantageous in that the kinetics are relatively slow and therefore reduction of the PCB concentration to an acceptable level requires extended time periods ranging from weeks to months, the soil must be completely dry for the destruction to take place, large quantities of the reagent are required, and the sulfoxide catalyst may potentially transport contaminants prior to their destruction. The Peterson U.S. Pat. No. 4,574,013 discloses a process wherein a heated slurry of contaminated soil is treated with a mixture of an alkaline constituent and a sulfoxide catalyst. However, this process is similarly disadvantageous in that the sulfoxide catalyst may transport contaminants into living systems, and the sulfoxide catalyst produces odorous compounds when heated to high temperatures and decomposes into combustible byproducts under elevated temperature conditions. This process is also disadvantageous in that it requires large amounts of reagents.
The Rogers et al U.S. Pat. No. 4,675,464 discloses a method for the chemical destruction of halogenated aliphatic hydrocarbons, and more particularly a method for the chemical destruction of ethylene dibromide. An alkali metal hydroxide is dissolved in an ethylene glycol and the resulting product is reacted with the halogenated hydrocarbon. Rogers et al further disclose that the reaction temperature should be maintained at 30.degree. C. or less to maintain the reaction products in solution.
The Pytlewski et al U.S. Pat. No. 4,400,552 discloses a method for the decomposition of halogenated organic compounds which employs a reagent comprising the product of the reaction of an alkali metal hydroxide with a polyglycol or a polyglycol monoalkyl ether, and oxygen. The Pytlewski et al U.S. Pat. Nos. 4,337,368 and 4,602,994 disclose similar methods of decomposing halogenated organic compounds. However, these methods are disadvantageous in that excess amounts of the alkali metal hydroxide and polyglycol reagents are required in order to obtain a homogeneous distribution throughout the contaminated material, for example soil, sediment, sludge or the like, which is treated. Similarly, the Brunelle U.S. Pat. Nos. 4,351,718 and 4,353,793 disclose methods for removing polyhalogenated hydrocarbons from nonpolar organic solvent solutions by treating the contaminated solutions with a mixture of polyethylene glycol and an alkali metal hydroxide. These methods are similarly disadvantageous in that excess amounts of reagent are required. Additional methods for removing and/or destructing halogenated organic compounds contained in contaminated materials are disclosed in the Howard et al U.S. Pat. No. 4,327,027, the Mendiratta et al U.S. Pat. No. 4,663,027, the Meenan et al U.S. Pat. Nos. 4,685,220 and 4,793,937, the Rossi et al U.S. Pat. No. 4,761,221, the Zeff et al U.S. Pat. No. 4,792,407, European Patent Application No. 118,858, Chemical Abstracts, Vol. 82, No. 139620P (1975) and Kornel et al, Journal of Hazardous Materials, 12 (1985), pages 161-176. However, these and additional processes known in the art for the removal and/or destruction of halogenated organic compounds in contaminated materials are inadequate in view of the time required for acceptable levels of removal and/or destruction, the use of excessive amounts of various reagents, the production of toxic and/or combustible byproducts, and/or the failure to obtain desired removal and/or destruction levels. Thus, a need exists for additional methods for the removal and/or destruction of halogenated organic compounds in contaminated materials, which methods overcome the disadvantages of the prior art.